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Everything posted by ikarus

  1. TheDeerDance

    You have some great shader work there
  2. Why not just sim them separately since you dont want them to interact?
  3. Can we get this in H15? http://www.cs.ubc.ca/~zhxx/IVOCK.html
  4. Houdini for Games - Frima Studio

    Those vids should be gifs
  5. The smoke solver as a whole is a navier stokes solving algorithm. The gas project non-divergent dop is only one step of the entire thing.
  6. Cloud Problem

    Having scale transforms on cameras can affect the volume step.
  7. Efficient FLIP workflows (mechanical animation)

    Using the default source method you won't get any kind of pressurized behavior, which I think is what your looking for. Source FLIP basically fills the source area with fluid (surface) and particles, but if that area is already full of fluid you get no additional quantity being added to the simulation. Try adding some divergence to your sourcing.
  8. Gas vorticle forces usually directly changes the velocity field. So if you want to visualize it and change it you'll need to create a separate vector field (which you can attach a vector volume viz to) and apply the vorticle forces to that custom field. Then you can do whatever modifications to that intermediate field and add it to the velocity field. If you have resizing volumes you can just use a gas match field referencing the velocity volume (you can also apply a vector volume viz to this as well).
  9. Is Nvidia Titan Z a worthwhile card for Houdini?

    Is that limited to windows or are we talking all platforms?
  10. laplacian.hipnc So i built the laplacian op and i get the same result from the sop volume analysis laplacian (slice1 to slice2) Comparing techniques it appears that splitting the divergence and gradient operations results in a loss of high frequency values (comparing slice2 to slice3 in the file) Problem with discretizing these pde formulas is the inherent loss of data from sample rate, so simplifying the algorithm to one step probably reduces data loss from sample rate. just my guess
  11. Have you tried making the laplacian calculation in a vop?
  12. I chopped my file from a fluid sim recreation in sops, but if you look at the formula for divergence you divide your sum of differences by 2*stepsize. I believe this comes from a need to have your final output be independent of your fluid resolution, though I don't know enough about descretizing pde equations to give a solid answer.
  13. divergence.hip finite difference divergence, the difference of neighboring voxels, summed over all axes, regularized over the step size of the grid, from a cfd standpoint atleast. good fluids cheat sheet http://http.developer.nvidia.com/GPUGems/gpugems_ch38.html
  14. I saw this was rolled out at siggraph asia 14 but haven't heard anything about this so far http://pages.cs.wisc.edu/~sifakis/project_pages/SPGrid.html There's some definite comp-sci wizardry happening here involving sparse memory paging that's rather difficult to comprehend fully. They compare it to VDB and atleast in the access test results they showed it has quite the speed improvement (What looks to be 10x) in access. Maybe we'll see a VDB-topper for volume data/simulation using techniques like this in the near future? Thoughts?
  15. SPGrid for adaptive smoke simulation

    The paper also includes their approach to simulation using the SPGrid structure.
  16. animated flip fluid source

    If its just vex based modifications yeah that would be the place to do it.
  17. snowflake and others

    These are gorgeous, nice work.
  18. eetu's lab

    I think this builds on good ideas for wet sand modelling, good effort!
  19. animated flip fluid source

    At it's simplest, you need a state attribute (0 - 1) that decides when to allow particles to partake in fluid simulation. Any particles who's state attrib isn't 1 will just have their position and velocity overwritten by the animation values in a geometry vop after the flip solve. flipanim.hip
  20. Made a greeble landscape as well
  21. Bifrost vs Houdini

    The naiad tech that bifrost is based from is decent and even better than houdini in certain situations regarding fluid simulation but it'll be years before Autodesk has these kind of suggested workflows commonplace in regular maya environments. Engine will be big by then though :v
  22. Fast Volume Lattice tool

    If you're doing your deformation in a volume vop, VDBs work with volume vops, you just need to be aware of the active voxel regions and adjust them according to the deformation.
  23. Iterate over unique pairs of points

    Why would you want to keep track of what particle pairs have been tested? If you're doing the detection/correction in VEX, each operation can only work on one point at a time anyway, your algorithm should result in the same output on both points of a collision. ie vex code runs on point A, finds B within the collision radius, applies correction to A based on B, then vex code runs on point B and would result in the equal (but opposite) correction from A.
  24. Hooke's law

    You could certainly build a spring-mass system in geometry dop / pop wrangle, but I couldn't see you getting very high point counts in this manner as spring systems need a good deal of substeps to be stable, which when combined with pc-lookups on dense point data, will become quite slow. Guess it depends on what resolution you're looking to achieve. The other thing is I don't think you will get the effect you want with spring constraints alone, if you're going for the snow clump effect.
  25. Hooke's law

    The disney snow simulation used a FLIP-based system of storing velocity and strain on the particles and calculating the forces and such on grids. That gives you easy access to gradient and divergence calculations involved in applying stress+strain based forces.